Nosocomial infections are any infections generated in the hospital. Many of these are a result of treatment by hypodermic-delivered injectable medications. These infections are secondary to the patient's original condition. According to the Centers for Disease Control and Prevention, in the United States alone, it has been estimated that as many as one hospital patient in ten (or 2 million patients a year) acquires a nosocomial infection. Estimates of the annual cost range from $4.5 billion to $11 billion and up. Nosocomial infections contributed to 88,000 deaths in the US in 1995. Nosocomial infections are even more alarming in the 21st century as antibiotic resistance spreads. Warning signs in some hospitals state “For every minute you are in a hospital, you will pick up from 8 to 15 bacteria on your hands.”
One of the most common vectors for transmission of viral and microbial infections is airborne. One mode by which airborne microbes infect patients is via ambient-microbe-laden air introduced into medicinal vials by nurses giving shots.
In current practice, ambient air is drawn into hypodermic needles and then injected into vials to pressurize the vials so as to prevent vacuum lock. This air is laden with airborne microbes, and they are then injected into the bottle, mix with the medicinal fluid where they may incubate over extended periods before the next use. They are then, or later, withdrawn into the hypodermic with the medicinal fluid and injected directly, sub-dermally into the patient, often directly into the blood-stream or intramuscularly. In addition, special medical fluids are introduced by hypodermics into IV lines (typically by Y-tube connectors or into the bags themselves), thus contaminating the IV fluid.
The reason for injecting ambient air into the vial is to overcome the vacuum-lock—that is, withdrawing fluid from the vial creates a vacuum so strong that the hypodermic cannot be filled. While open medicine bottles have been abandoned as unsanitary for over 50 years, there has been little, if any, recognition of the introduction, at the time of filling of the hypodermic, of microbes in the ambient air introduced into closed vials via the step of first pressurizing the vial with the hypodermic full of ambient air.
Soft, pliable plastic blood bags and saline bags are used for gravity feed of fluids to bed-bound patients. No vacuum lock occurs, as the bags collapse under external air pressure. In addition such bags are always elevated so the fluid is gravity fed. In addition the fluid is usually introduced into a vein, where the moving blood accepts the added fluid. For uphill drip systems, Peery et al discloses in U.S. Pat. No. 4,386,929 an elastically pressurized medicinal fluid container. In contrast, in sub-dermal injection by hypodermic, the injected fluid is forced into muscle under considerable pressure to form its own bolus.
Vacuum lock issues have been addressed in far different arts—including ink jet cartridges, baby bottle nipples, wine bottle stoppers and the like. An example of internal bladders plus bubble vents to address “over driving” of ink cartridges and fade-out during printing caused by vacuum lock issues in the ink jet cartridge field is U.S. Pat. No. 5,686,948 in Class 347/85 (also see 347/86, 87 and Class 141/2, 18 and 19). However, there the issue is different: There, air can be inlet through the fluid ink by the bubble vent 53, while the “lungs” 44, 46 (bladder and spring) function to provide back pressure and to compensate for the relatively constant rate of withdrawal during printing. Inlet air fills the void left by used ink.
In contrast, withdrawal from a medicine vial is in large, intermittent aliquots—something the ink jet cartridge is not designed to handle. Further, air in contact with medicinal fluid would contaminate it.
Some hospital and clinical protocols call for filling hypodermics from vials, especially hazardous drugs or biologics, under conditions that protect health care workers and patients, including hoods or other areas with ISO Class 5 environment with protective engineering controls and aseptic practices. However, it has been determined that in a USP 797 standard laminar flow hood there are still on the order of 20,000 contaminants per cubic foot of air.
There is an urgent need in the art for solving the problems specific to transmission of nosocomial infections via introduction of microbes into medicinal vials during pressurization by hypodermic needles.